General-purpose, vertically operating doors often have a flexible curtain that opens by rising from a vertical set of tracks installed alongside a doorway. Upon rising, the curtain transfers from the vertical tracks over to an overhead storage system. The actual design of the storage system may vary depending on the available space above the doorway and other considerations. An overhead storage system, for example, can be in the form of a take-up roller that draws in the curtain to open the door, or the storage system can be a set of horizontal, vertical, inclined, or coiled tracks that lead to the set of vertical tracks alongside the doorway.
Some vertically operating doors also include some type of protective breakaway feature that allows the curtain to temporarily separate from its guide tracks in the event of a collision such as, for example, the door's curtain being accidentally struck by a forklift passing through the doorway while door is only partially open.
Due to a vertically operating door's numerous intricate parts such as the door's vertical tracks; seals; overhead storage system; breakaway feature; and even the curtain itself, which can be comprised of multiple interconnected sheets and perhaps a window, such doors can be difficult to keep clean in environments that demand cleanliness. Many doors in the food and drug industry, for instance, need to be periodically washed down and sanitized in order to prevent product contamination.